The fingerprint recognition technique has been widely applied to mobile smart device. Taking a smart phone as an example, the fingerprint recognition has become a main configuration of the smart phone. A pressing-type of fingerprint recognition has gradually occupied the mobile smart device market due to features of small size and high rate of recognition and the like while providing security. Presently, the pressing-type fingerprint recognition chip exists as an individual block, which is applied to a front physical key of the device or is individually arranged on a housing of the device. With the development of the fingerprint recognition technique, a much larger screen proportion and screen space is required in the mobile smart device, and a more humanized unlock experience is also required in the same high security level.
In the screen-integrated fingerprint unlocking modules which are currently available in the market, fingerprint module is hidden under the touch screen, which could provide high screen proportion while maintaining a good effect on the fingerprint unlocking. However, since the fingerprint module is located at the edge of the screen and the location is fixed, the comfort degree of usage is lowered.
An integrated apparatus, in which a fingerprint module and a touch screen or a touch pad are integrated, does not have a fixed detecting button, therefore, when the fingerprint unlocking function needs to be implemented, a physical button or a power button needs to be pressed first to activate the fingerprint module, and then, a finger is pressed on the touch screen or above the touch pad (a certain region or any region of the entire screen) for fingerprint collection, and then the collected fingerprint is received and matched to unlock the device. From the using habit, the entire unlocking process is too long with complex steps, which dramatically lowers the user's experience.
However, if a technique of “Cold Wake Up” is applied to the integrated apparatus, the fingerprint module has to maintain a normal operation state, so as to wait for a user's touch to collect the fingerprint, but enabling the fingerprint scanning function of the entire plane for long time causes relatively high power consumption. In the fingerprint recognition module of the current mobile smart device, the fingerprint unlocking function is implemented by using capacitance sensing. The fingerprint module scans a few pixels in fixed positions with intervals and detects the capacitance variance to achieve the finger touch detection function. A relatively high resolution, generally greater than 300 DPI (dots per inch), is required, and thus the power consumption is relatively high when the fingerprint module scans fingerprint. Therefore, two below problems exist when the “Cold Wake Up” technique for detecting finger touches is applied on the integrated apparatus:
1. High power consumption: the entire area of the touch screen or touch pad is dozens of times of that of an individual fingerprint module. This means that the integrated apparatus in which the fingerprint module and the touch screen or pad are integrated, needs more pixels to participate in the finger touch detection. Thereby, the power consumption becomes higher, and it is impossible to achieve a long time standby detection with low power consumption.
2. Low recognition degree: when the “Cold Wake Up” to detect a finger touch is implemented by capacitance sensing on the basis of less pixels, the sensing of finger presses of different persons is different, and the fault tolerance in respect of waterproof and preventing accidently triggering is relatively low. When a mobile smart device is placed in the pocket or when the screen is wet, accidently triggering is easy to occur. Such long term errors can affect the user's experience, and also increase overall power consumption.